1. Field of the Invention
The present invention relates to a setting tool for driving in fastening elements and including a piston guide having a hollow chamber, a setting piston axially displaceably arranged in the hollow chamber of the piston guide and having a piston head, a piston stem, and a conical active surface, and a piston stop device for the setting piston and arranged in a setting direction end region of the hollow chamber, with the piston stop device having a stop member adjoining the hollow chamber in the setting direction and having a conical active surface that cooperates with the conical active surface of the setting piston.
2. Description of the Prior Art
Setting tools of the above-described type are driven with solid, gaseous, or fluid fuels or with compressed air. In combustion-driven setting tools, the setting piston is driven by combustion gases. With these setting tools, fastening elements, such as, e.g., nails or bolts are driven in constructional components.
U.S. Pat. No. 4,828,003 discloses a setting tool in which between the piston guide and the bolt guide, there are arranged one after another a rigid ring and an elastic ring. In the elastic ring, a further rigid ring is arranged that limits the stroke of the first rigid ring. The first rigid ring has a leadthrough conically narrowing in the setting direction for the piston stem. The setting piston has, adjacent to the first rigid ring, a conical surface, with the conical profile of the conical surface of the setting piston and the conical surface of the leadthrough being complementary to each other.
The drawback of the structure of the above-discussed U.S. patent consists in that under certain operational conditions, the setting piston with its conical surface can be jammed in the conical leadthrough of the first rigid ring. Such jamming often leads to breakdown of the setting tool parts and to interruptions of the operation of the setting tool as after a while, release of jamming is not possible.
Accordingly, an object of the present invention is to provide a setting tool in which the drawback of the setting tool of the above-mentioned U.S. patent is eliminated, i.e., jamming between the setting piston and the stop ring is prevented.